The best PPT for a reef tank, referring to salinity in parts per thousand, is 35 ppt.
Understanding PPT in Reefkeeping
In the context of reef aquariums, PPT stands for parts per thousand. This is a common unit used to measure salinity, which is the total amount of dissolved salts in a body of water. Maintaining the correct salinity level is crucial for the health and survival of marine life, including corals, fish, and invertebrates.
Recommended Salinity Range
Based on standard recommendations for reef aquariums, the ideal salinity target is 35 ppt. This level closely mimics the salinity of natural ocean water, which is the native environment for most reef inhabitants.
According to the provided reference:
- Reef aquariums should contain saltwater mixed to 35 ppt salinity.
- This corresponds to a specific gravity range of 1.024 - 1.026.
Keeping your reef tank within this target PPT and specific gravity range ensures a stable environment that supports the biological processes of your tank inhabitants.
Measuring and Maintaining Salinity
Maintaining consistent salinity is vital. Here's how you can measure and manage it:
- Measurement Tools:
- Refractometer: A common and generally accurate tool that uses light refraction to determine salinity or specific gravity.
- Hydrometer: A simpler, less expensive tool that measures specific gravity by flotation. Requires careful use for accuracy.
- Electronic Salinity Tester: Provides a digital reading, often considered highly accurate but requires calibration.
- Mixing Saltwater:
- When preparing new saltwater for water changes or topping off after evaporation (using RO/DI water), you need to mix a marine salt mix with purified water (Reverse Osmosis/Deionized or RO/DI water).
- The reference notes that every brand of salt mix will be slightly different in terms of how much salt is needed per gallon of water to reach a particular salinity level like 35 ppt. Always follow the manufacturer's instructions on the salt mix packaging as a starting point, but verify the final salinity with a refractometer or hydrometer before adding it to your tank.
- Evaporation: As water evaporates from your tank, the salt is left behind, increasing salinity. Using an auto top-off (ATO) system with fresh RO/DI water or manually adding RO/DI water daily helps prevent salinity from creeping up.
Here's a quick reference based on the common target:
| Measurement | Ideal Target Range |
|---|---|
| Salinity (PPT) | 35 ppt |
| Specific Gravity | 1.024 - 1.026 |
Targeting 35 ppt ensures your reef tank provides an optimal environment for a wide variety of corals, fish, and other reef-dwelling organisms.
